Quantitative charging apparatus

ABSTRACT

A quantitative charging apparatus of the present invention comprises a large charging storage cup and a plurality of additive storage cups having different capacity ratios in which articles are filled with even cupfuls. The capacity of the large charging storage cup is set so as to store the articles having a weight which is smaller than and close to a target weight. The articles within the large charging storage cup is weighed by a load cell to obtain a large charging weight, and the weights of the articles within the additive storage cups are weighed by other load cells. A control device finds, as an underweight, the difference between the large charging weight and the target weight, and selects the suitable combination of the additive storage cups having capacities which are close to the underweight. The articles within the selected additive storage cups are supplied into a container together with the articles within the large charging storage cup through a chute. In addition, a plurality of additive auxiliary cups may be provided. In this case, if the maximum capacity of the additive storage cups is Vmax, the reference value of the bulk density of the articles is d, and the maximum dispersion ratio of the bulk densities is Z, the capacities of the additive storage cups and additive auxiliary cups are determined in such a manner that the total weight of the articles within the additive auxiliary cups is the closest to 2ZdVmax.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of the application having Ser. No. 08/628,491,filed Apr. 5, 1996.

FIELD OF THE INVENTION

The present invention relates to a quantitative charging apparatus forfeeding articles having great variations in volumetric weight into astorage cup of a predetermined capacity so that quantitative charging isperformed, and more particularly to a quantitative charging apparatuscomprising a large charge storage cup for storing a large or bulk chargeof a plurality of additive storage cups having different capacities forstoring additive charges to make up an underweight and additiveauxiliary cups which can be used, if necessary, so that it is possibleto provide a more accurate weight relative to a target weight within awide range.

PRIOR ART

Quantitative charging of powdery or granular articles has a longtradition. Of constant quantity filling methods, volumetric weighing isa method which has been widely adopted. However, volumetric weighing hasbeen gradually replaced with weighing by weight. The main reason is thatit has become necessary to weigh a chemical compound more accurately,for example. This is a problem which has not been very important forweighing agricultural products such as rice and wheat in the past. FIG.9 shows a typical example of a conventional quantitative chargingapparatus for powder.

In the quantitative charging apparatus of FIG. 9, a target weight is setby a 100% setter 51, 90% of the target weight is set as a cut value by acut value setter 52, and articles are supplied into a weighing hopper 53while weighing them. To shorten a weighing time as much as possible inthis apparatus, it is necessary to perform charging with an increasingfeeding rate which is realized by increasing the amplitude of a feeder55 until up to 90% of a predetermined quantity is fed to hopper 53. Thisis called "large or bulk quantity charging", "rough charging" or "90%charging". When a charging quantity reaches about 90%, the amplitude ofthe feeder 55 is decreased under the control of a control device 56, andfine charging is then performed for the remaining 10%. Charging isstopped when 100% of the target weight is reached. Such fine charging iscalled "small or dribble quantity charging". Upon completion ofcharging, the articles are filled into a container (not shown) from alower portion of the weighing hopper 53. The quantitative chargingapparatus of this type performs weighing while supplying the articles,and does not increase charging speed.

In order to solve these problems, Japanese Laid-Open Patent Nos.50-120660 and 62-9226 have disclosed a quantitative charging apparatusin which a charging speed can be enhanced. According to the quantitativecharging apparatus of this type, articles whose weights are smaller thanand close to a target weight are stored in a large charge storage cup,and a plurality of auxiliary cups having the same capacities areprovided for making up the underweight. Such an apparatus performsquantitative charging by utilizing a variation in the weight of thearticles stored in each auxiliary cup. More specifically, an underweightis obtained by subtracting the weight of the articles stored in thelarge charging storage cup from the target weight, and a combination ofauxiliary cups is selected having combined capacities which are theclosest to the underweight. Thus, a plurality of auxiliary cups havingthe same capacities are provided so that articles having a weight closeto the target weight can be delivered to a container. The quantitativecharging apparatus of this type does not perform weighing while thestorage cups are being filled. Consequently, the charging speed can beincreased.

However, the quantitative charging apparatus described above has thefollowing problem. In the case where the weight of the articles to besupplied into the large charging storage cup has a great variation, itmay be impossible to make up the underweight even if all the auxiliarycups are selected. In order to solve this problem, the size of theauxiliary cup may be increased. In some cases, however, the large sizeof the auxiliary cups may make it impossible to find a combination ofweights which will provide an acceptable weight within the allowablerange. This is because the large size of the cups prevents fine(precise) adjustment of the weight. In order to solve this problem, thesize of the auxiliary cup may be decreased. In some cases, however, theunderweight cannot be made up even if all the auxiliary cups areselected. Accordingly, many auxiliary cups should be provided.

The present invention solves these problems associated with the priorart. It is an object of the present invention to provide a quantitativecharging apparatus capable of controlling and more finely (precisely)adjusting the weight of articles within a wide range, and capable ofperforming high-speed charging.

SUMMARY OF THE INVENTION

The present invention provides a quantitative charging apparatuscomprising a large (bulk) charge storage cup for storing articles havinga weight which is smaller than and close to a target weight W_(o), aplurality of additive storage cups which store the articles for additivecharging and have at least two different capacities, first weighingmeans for weighing, as a large (bulk) charge weight W_(a), the articlessupplied into the large charge storage cup, a plurality of secondweighing means provided in the additive storage cups for weighing thearticles supplied into the additive storage cups respectively, andcontrol means for determining, as an underweight W_(b), a difference(W_(o) -W_(a)) between the target weight W_(o) and the large chargingweight W_(a), selecting the combination of the additive storage cupshaving capacities which are the closest to the underweight W_(b) basedon the weights of the articles stored in the additive storage cups whichare obtained by the second weighing means, and discharging the articleswithin the selected additive storage cups together with the articleswithin the large charge storage cup.

Furthermore, at least part of the additive storage cups may have acapacity ratio of

1:r¹ :r² : . . . :r^(k-1) : . . . r^(n-1)

(r is a positive real number, 0<k (integer)<=n, n<=the number of theadditive storage cups). In addition, the positive real number r may be2.

The quantitative charging apparatus according to the present inventioncomprises a large (bulk) charge storage cup for storing large chargesand a plurality of additive storage cups for storing additive charges tomake up the large charge. The capacity of the large charge storage cupis set so as to store articles having a weight which is smaller than andclose to the target weight W_(o). Furthermore, the additive storage cupshave at least two different capacities, and divide the articles foradditive charging into a plurality of different capacities for storage.The articles can be supplied into the large charge storage cup and theadditive storage cups at almost the same time.

The articles supplied into the large charge storage cup are weighed byfirst weighing means to have a large charge weight W_(a). The additivestorage cups have second weighing means respectively. The articles foradditive charging which are stored in the additive storage cups areweighed by the second weighing means respectively. The articles can beweighed by the first and second weighing means almost simultaneously.

Control means determines an underweight W_(b), W_(o), -W_(a) bysubtracting the large (bulk) charge weight W_(a) obtained by the firstweighing means from the target weight W_(o). Since the capacity of thelarge charge storage cup is set to store articles having a weightsmaller than the target weight W_(o), the underweight W_(b) always has apositive value. Then, the control means selects the combination ofadditive storage cups having capacities which are the closest to theunderweight W_(b) based on the weights of articles within the additivestorage cups obtained by the second weighing means respectively, andeffects the discharge of the articles within the selected additivestorage cups and within the large charge storage cup.

The calculation for obtaining the underweight W_(b) and the selection ofthe combination of additive storage cups can be performed instantly by acomputer or the like. Consequently, high-speed charging can be realized.Since the quantitative charging apparatus of the present inventioncomprises a plurality of additive storage cups having at least twodifferent capacities, the weight of the articles can be controlled andadjusted more finely (precisely) within a wide range.

Furthermore, the capacity ratio of n additive storage cups (n<=thenumber of the additive storage cups) is set to

1:r¹ :R² : . . . :r^(k-1) : . . . :r^(n-1)

so that the weight of the articles can be controlled and adjusted muchmore finely within a wider range. More specifically, if the positivereal number r is set to 2 in the above expression, the weight can becontrolled and adjusted more precisely within the wide range.

In the embodiment described above, if the bulk densities of the articleswithin the additive storage cups 4a to 4e vary in different directionswith respect to a reference bulk density, the articles cannot beprecisely adjusted within a wide range. However, a different embodimentfor the quantitative charging apparatus of the present invention may beequipped with a structure which permits more precise adjustment within awide range even if the bulk densities of the articles are changed. Inthis embodiment, the quantitative charging apparatus comprises a largecharge storage cup provided with weighing means for storing articleshaving a weight which is smaller than and close to a target weight, aplurality of additive storage cups provided with weighing means, theadditive storage cups having at least two different capacities forstoring articles for additive charging so as to make up the underweightobtained by subtracting the weight of the articles within the largecharge storage cup from the target weight, a control device forselecting a combination of additive storage cups to stepwise(incrementally) change the weight of articles for additive chargingaccording to a predetermined charge weight difference, and one or aplurality of additive auxiliary cups provided with weighing means forcorrecting a gap in the charge weight difference caused by a variationin bulk density of the articles for additive charging which is stepwise(incrementally) changed depending on the change of the combination whenthe combination of the additive storage cups is selected by the controldevice.

The quantitative charging apparatus according to the present inventionmay have a structure in which the additive storage cups include at leastm additive storage cups having the following capacity:

a, as¹, as², . . . , as^(k-1), . . . , as^(m-1)

a : the capacity of the additive storage cup as a reference

s: a positive real number

0<k (integer)<=m, m<=the number of the additive storage cups.

Furthermore, the quantitative charging apparatus according to thepresent invention may have a structure in which the additive auxiliarycups include at least p additive auxiliary cups having the followingcapacity.

B, bt¹, bt², . . . , bt^(k-1), . . . bt^(p-1),

b: the capacity of the additive auxiliary cup as a reference

t: a positive real number

0<k (integer)<=p

In the quantitative charging apparatus according to the presentinvention, the positive real numbers t and s may be equal to each other.

Furthermore, the positive real numbers t and s may be 2.

The quantitative charging apparatus according to another embodiment ofthe present invention may have a structure in which when the maximumdispersion (variation) ratio of the bulk densities of the articleswithin the additive storage cups is Z, the maximum volume of the madditive storage cups is V_(max) and the total capacity of the padditive auxiliary cups is A, the number p of the additive auxiliarycups is an integer which satisfies the following equation: ##EQU1##

The quantitative charging apparatus according to this embodiment of thepresent invention can include a structure in which the large chargestorage cup comprises a main charge storage cup and a subtractiveauxiliary cup having weighing means respectively, the subtractiveauxiliary cup holding articles without discharge so that the chargingweight difference is decreased.

The quantitative charging apparatus according to the present inventioncan add a structure in which the additive auxiliary cup is a single cup,and the additive auxiliary cup and the subtractive auxiliary cup havecapacities which can store the articles having a weight of (2ZdV_(max)-ad) to (2ZdV_(max) +ad) when the maximum volume of the additive storagecups is V_(max).

The quantitative charging apparatus according to the present inventioncomprises a large charge storage cup for storing a rough (bulk) chargeof articles, that is, a large charge of articles, and a plurality ofadditive storage cups having at least two different capacities formaking up an underweight relative to a target weight. The large chargestorage cup and the additive storage cups have weighing meansrespectively. The control device selects the combination of the additivestorage cups having capacities which are the closest to the underweightbased on the weights of the articles within the additive storage cupsobtained by the weighing means.

By changing the combination of the additive storage cups which should beselected, the weight of articles for additive charging are stepwise(incrementally) changed according to a predetermined charge weightdifference. However, if there is a variation in the bulk density of thearticles in the additive storage cups, a partial gap is caused on thecharge weight difference of the articles due to the change of thecombination of the additive storage cups in some cases. The apparatus ofthe present invention comprises one or a plurality of additive auxiliarycups for correcting the gap in the charging weight difference. Accordingto the selected combination of the additive storage cups, if the chargeweight difference is increased, the articles which should be suppliedfrom the selected additive storage cups are partially replaced with thearticles supplied from the additive auxiliary cups so that theunderweight is made up. The number and capacities of the additiveauxiliary cups are determined in consideration of the dispersion ratioof the bulk densities of the articles.

In the apparatus of the present invention, the additive storage cups mayinclude at least m additive storage cups having a capacity expressed asfollows:

a, as¹, as², . . . , as^(k-1), . . . , as^(m-1)

a: the capacity of the additive storage cup as a reference

s: a positive real number

0<k (integer)<=m, m<=the number of the additive storage cups

According to such a structure, the combination of the additive storagecups is changed so that the underweight can be made up at almost regularintervals. Consequently, it is possible to decrease the capacity of theadditive auxiliary storage cup which corrects the gap in the chargeweight difference of the articles for addition.

In the apparatus of the present invention, the additive storage cups mayinclude at least p additive auxiliary cups having a capacity expressedas follows:

b, bt¹, bt², . . . , bt^(k-1), . . . bt^(p-1)

b: the capacity of the additive auxilliary cup as a reference

t: a positive real number

0<k (integer)<=p

According to the structure of the auxiliary cup, the gap in the chargeweight difference caused by the variation in bulk density of thearticles can be made up at almost regular intervals.

When the positive real numbers t and s are equal to each other and setto 2, the same effects can be obtained by the comparatively simplestructure.

In the apparatus having the structure in which the positive real numberst and s are 2, the number p and capacities of the additive auxiliarycups can be determined as follows. If the reference value of the bulkdensity of the articles within the additive storage cups is set to d andthe maximum dispersion ratio of the bulk density of the articles is setto Z, a maximum charge weight difference W_(max) is generated on thearticles for additive charging when the articles having the maximum bulkdensity are supplied into the additive storage cup having the maximumcapacity and the articles having the minimum bulk density are suppliedinto other additive storage cups. In other words, the maximum chargeweight difference W_(max) is obtained as follows: ##EQU2## If (2^(m-1)-1) is nearly equal to 2^(m-1) and the maximum volume of the m additivestorage cups is expressed by V_(max), the following equation isobtained:

    W.sub.max nearly equals to 2Zd (a2.sup.m-1)=2ZdV.sub.max

In other words, the maximum charge weight difference W_(max) which maybe generated is twice as great as the weight of the articles whose bulkdensity has a reference value d that are supplied to the maximumcapacity additive storage cup. If the total weight of the articleswithin the additive auxiliary cups is greater than the maximum chargeweight difference W_(max), it is possible to make up the maximumcharging weight difference W_(max) by selecting the combination of theadditive auxiliary cups. More specifically, if the total capacity of thep additive auxiliary cups is expressed by A, the following relationshipshould be obtained: ##EQU3##

Accordingly, the following equation should be formed: ##EQU4##

According to another structure of the present invention, the largecharge storage cup can be formed by a main charge storage cup and asubtractive auxiliary cup. In the apparatus having such a structure, thesubtractive auxiliary cup holds the articles without discharge so thatthe maximum charge weight difference W_(max) can be decreased.

Furthermore, the apparatus may have a structure (system) in which thecapacity of the subtractive auxiliary cup is set so as to store thearticles having a weight of (2ZdV_(max) -ad) to (2ZdV_(max) +ad).According to such a system, it is possible to perform correction so asto almost offset the maximum charge weight difference W_(max).

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation showing a first example of aquantitative charging apparatus according to the present invention;

FIG. 2 is a circuit block diagram showing control means provided in thequantitative charging apparatus in FIG. 1;

FIG. 3 is a flowchart showing the quantitative charging method which isperformed by using the quantitative charging apparatus in FIG. 1;

FIG. 4 is a diagram showing a large step increase (charging weightdifference) between different additive charging weights due to variationin bulk density of the articles in additive storage cups of thequantitative charging apparatus in FIG. 1;

FIG. 5 is a schematic representation showing a second example of aquantitative charging apparatus having an additive auxiliary cupaccording to the present invention;

FIG. 6 is a schematic representation showing a third example of aquantitative charging apparatus having a subtractive auxiliary cupaccording to the present invention;

FIG. 7 is a diagram for explaining the function of the additiveauxiliary cup;

FIG. 8 is a diagram for explaining the function of the subtractiveauxiliary cup; and

FIG. 9 is a schematic representation showing a quantitative chargingapparatus having a vibrational feeder according to the prior art.

DETAILED DESCRIPTION OF THE INVENTION

Examples of the present invention will be described in detail withreference to the drawings.

Example 1

FIG. 1 shows the schematic structure of a quantitative chargingapparatus according to an example 1 of the present invention. Thequantitative charging apparatus according to the present example is usedto charge (load) a predetermined container such as a box or a bag witharticles having a target weight W_(o), and comprises a large (bulk)charge storage cup 1 and five additive storage cups 4a to 4e for storingarticles. Articles are supplied from a charging apparatus 11 into thelarge charge storage cup 1 and the five additive storage cups 4a to 4ewith even cupfuls(i.e., each cup 4a to 4e is filled up to but not higherthan its brim) at almost the same time. The large storage cup 1 has aload cell 7. The articles supplied into the large charge storage cup 1are weighed by the load cell 7. The five additive storage cups 4a to 4ehave load cells 2a to 2e respectively by which the articles for additivecharging are weighed. The outputs of the load cells 7 and 2a to 2e areinput to a control device which has a circuit shown in FIG. 2.

A gate 8 for discharging the articles is disposed in a bottom portion ofthe large charge storage cup 1, while five gates 6 which open and closeindependently of each other are disposed in the additive storage cups 4ato 4e, respectively. The articles within the large charge storage cup 1and the additive storage cups 4a to 4e are discharged into a container10 such as a box or a bag through a chute 9. The gate 8 and the fivegates 6 open and close under the control of the aforementioned controldevice.

A capacity ratio among the additive storage cups 4a to 4e is obtained bysetting r=2 and n=5 in the expression r^(k-1) (r is a positive realnumber, k<=n, n=the number of the additive storage cups), that is,1:2:4:8:16.

As shown in a block diagram of FIG. 2, the output of the load cell 7which weighs the articles supplied into the large charge storage cup 1and the outputs of the load cells 2a to 2e which weigh the articles inthe additive storage cups 4a to 4e, are amplified by amplifiers 21 andconnected to a multiplexer 22. The multiplexer 22 switches the output ofeach amplifier 21 by time sharing. Then, the switched output is input toan A/D converter 23. The A/D converter 23 converts the input analog datato digital data to be processed by a CPU (central processing unit) 24.The CPU 24 performs processing according to a program stored in a ROM(read only memory) 25. In this case, a RAM (random access memory) 26 istemporarily used. Data such as a target weight W_(o), the bulk densityof the articles and the like are input to and stored in a nonvolatileRAM 30 through a keyboard 27. The opening and closing of the gate 8 andthe five gates 6 based on the result of processing of the CPU 24 arecontrolled through an input-output 28. An indicator 29 indicates theweight of the articles in the large charge storage cup and additivestorage cups, a value set to the nonvolatile RAM 30 and the like.

The apparatus of the present example performs quantitative chargingaccording to a flowchart shown in FIG. 3. At Step 32, the container 10is placed below a lower portion of the chute 9. At Step 33, articles aresupplied from the charging apparatus 11 to the large charge storage cup1 and to the five additive storage cups 4a to 4e. At Step 34, thearticles supplied to the large charge storage cup 1 are weighed as alarge (bulk) charge weight W_(a) by the load cell 7. At the same time,the articles supplied to the additive storage cups 4a to 4e are weighedby the load cells 2a to 2e.

At Step 35, an underweight W_(d) =W_(a) -W_(o) is determined. At Step36, a combination of additive storage cups yielding a combined weight ofarticles closest to the underweight W_(d) is selected. At Step 37, thearticles within the additive storage cups of the selected combinationand the articles within the large charge storage cup 1 are thendischarged into the container 10. The filled container is replaced withan empty container at Step 38, and the process is then repeated fromStep 32.

According to the present example, the capacity ratio among the additivestorage cups 4a to 4e is 1:2:4:8:16. This means that the articles inthese cups have weights ranging from 1 to 31 times as great as that ofthe articles stored in the smallest additive storage cup 4a.Consequently, the weight of articles delivered to the container 10 canbe controlled and adjusted finer (more precisely) within a wide range.The weighing of the large charge weight W_(a) is performedsimultaneously with that of the articles within each additive storagecup. In addition, the calculation for obtaining the underweight W_(d)and the selection of the combination of additive storage cups havingcombined capacities closest to the underweight W_(d) are performed at ahigh speed by the CPU 24. Consequently, the charging speed is very high.

While five additive storage cups are described in the above example, thepresent invention is not restricted thereto and the number of additivestorage cups can be varied. While a positive integer r is 2 has beendescribed in the above example, the present invention is not restrictedthereto and other integers or decimal numbers can be selected.

The quantitative charging apparatus according to the present inventioncomprises a large charge storage cup for large charging, and a pluralityof additive storage cups having at least two different capacities forperforming additive charging to make up the difference between the largecharge and the target weight. Consequently, the weights of the articlescan be controlled and adjusted finer (more precisely) within the widerange. Since the weighing of the large charge weight W_(a) is performedsimultaneously with that of the articles within the additive storagecups, the charging speed is very high. In addition, the calculation forobtaining the underweight W_(d) and the selection of the combination ofadditive storage cups containing articles having combined weightsclosest to the underweight W_(d) can be performed at a high speed by acomputer or the like. Consequently, the charging speed is increased.

According to the apparatus shown in FIG. 1, if the bulk densities of thearticles within all the additive storage cups 4a to 4e vary in the samedirection relative to a reference value, a difference in charging weightof the articles for addition which can be prepared by the combination ofthe additive storage cups 4a to 4e is equal. For example, when the bulkdensity of the articles is the same as the reference bulk density, e.g.1, all of the differences in charging weight of the articles are also 1.When the bulk density shifts to the plus direction, e.g. 1.1, all of thedifferences in charging weight of the articles are 1.1. Consequently,the underweight W_(d) can be made up by additive charging within acapacity ratio of 1 to 31 irrespective of the value thereof. However, ifthe bulk density of the articles within the additive storage cups 4a to4e varies in different directions relative to the stated referencevalue, the following problems arise. For example, assume that the bulkdensities of the articles within the additive storage cups 4a to 4d(having a capacity ratio of 1:2:4:8) increase by 20%, and that the bulkdensity of the articles within the additive storage cup 4e (having acapacity ratio of 16) decreases by 20%. For simplicity, if the referencebulk density of the articles is 1, then the articles for additioncontained in the combination of the additive storage cups 4a to 4d(having a total capacity ratio of 15) have a weight of 1.2×15=18.0. Thearticles for addition contained in the additive storage cup 4e (having acapacity ratio of 16) have a weight of 0.8×16=12.8. The value of 12.8can be made up by a combination of other additive storage cups 4a to 4d.Hence, the additive storage cup 4e has no significance.

On the other hand, assume that the bulk densities of the articles withinthe additive storage cups 4a to 4d decrease by 20% and that the bulkdensity of the articles within the additive storage cup 4e increases by20%. In this case, the articles for addition contained in thecombination of the additive storage cups 4a to 4d (a total capacityratio is 15) have a weight of 0.8×15=12.0. The articles for additioncontained in the additive storage cup 4e (having a capacity ratiogreater than that of the combined additive storage cups by 1) have aweight of 1.2×16=19.2. As shown in FIG. 4, the articles for additionwhich are prepared have weights of 11.2, 12.0, 19.2 and 20.0. Thecapacity ratio of 15 to 16 causes a very big difference in chargingweight of 19.2-12.0=7.2 where the weights of the articles cannot beadjusted finer.

The following quantitative charging apparatus according to the presentinvention has a structure in which the weights of the articles can beadjusted finer within the wide range even if the bulk densities of thearticles vary.

Example 2

FIG. 5 shows the schematic structure of a quantitative chargingapparatus according to an example 2 of the present invention. Thequantitative charging apparatus according to the present example is usedto charge a predetermined container such as a box or a bag with articleshaving a target weight W_(o), and comprises a large charge storage cup 1for storing a large (bulk) charge of articles, five additive storagecups 4a to 4e for additive charging, and three additive auxiliary cups14a to 14c for correcting the charging weight difference. For example,articles are supplied from a charging apparatus 11 into the large chargestorage cup 1, the additive storage cups 4a to 4e and the additiveauxiliary cups 14a to 14c with even cupfuls (i.e., each cup 4a to 4e isfilled up to but not higher than its brim) at almost the same time. Thelarge charge storage cup 1 has a load cell 7. The articles which aresupplied into the large charge storage cup 1 are weighed by the loadcell 7. The five additive storage cups 4a to 4e have load cells 2a to2e, respectively, by which the articles for additive charging areweighed. According to the apparatus of the present example, furthermore,the additive auxiliary cups 14a to 14c have load cells 12a to 12c,respectively. The outputs of the load cells 7, 2a to 2e and 12a to 12care input to a control device (not shown).

A gate 8 for discharging the articles is disposed in a bottom portion ofthe large charge storage cup 1, while gates 6 and 16 which open andclose independently of each other are disposed in the additive storagecups 4a to 4e and the additive auxiliary cups 14a to 14c respectively.The articles within the large charge storage cup 1, the additive storagecups 4a to 4e and the additive auxiliary cups 14a to 14c are dischargedinto a container 10 such as a box or a bag through a chute 9. The gates8, 6 and 16 open and close under the control of the aforementionedcontrol device which is not shown.

According to the present example, a capacity ratio among the additivestorage cups 4a to 4e is obtained by setting s=2 and m=5 in theexpression S^(k-1) (s is a positive real number, k<=m, m=the number ofthe additive storage cups), that is, 1:2:4:8:16. Accordingly, if thesmallest additive storage cup 4a acts as a reference and has a capacitya, articles for additive charging having capacities of 1a to 31a (2.sup.-1=31a) are prepared. If the bulk density of the articles has areference (average) value d, a difference in charging weight of thearticles for additive charging has a value ad. More specifically, if thebulk density has the reference value d, the articles for additivecharging can be changed by ad.

A capacity ratio among the additive auxiliary cups 14a to 14c can be setby using an adequate positive real number t in the expression t^(k-1) (tis a positive real number, 0<k (integer)<=p). According to this capacityratio, the number p of the additive auxiliary cups can be determined.According to the present example, t and s have the same values, i.e., tis set to 2, the smallest additive auxiliary cup 14a acts as areference, and a capacity b is set to the capacity a of the smallestadditive storage cup 4a. In this case, the weights of the articleswithin all the additive auxiliary cups are expressed by the followingequation: ##EQU5##

The number p of the additive auxiliary cups is determined in such amanner that the combined weight of the articles within all the additiveauxiliary cups is greater than 0.4×16ad=6.4ad in which the maximumdispersion ratio of the bulk densities of the articles Z=0.2, m=5 ands=2 are substituted for (2dV_(max) =2Zdas^(m-1)). In other words, thenumber p of the additive auxiliary cups is 3(7ad) according to thepresent example. The capacities of the three additive auxiliary cups 14ato 14c are ad, 2ad and 4ad according to the ratio obtained by t^(k-1)wherein t=2, and k=1, 2, 3.

According to the present example, additive auxiliary cups 14a to 14chaving the same capacities as those of the three smaller additivestorage cups 4a to 4c are provided. Consequently, a maximum chargeweight difference W_(max) 6.4ad which is obtained by the structure(system) of the present example can be corrected by the same chargeweight difference as that of the additive storage cups 4a to 4c.

Example 3

FIG. 6 is a schematic drawing of a quantitative charging apparatusaccording to a third example of the present invention. The apparatus ofthe present example differs from the apparatus shown in FIG. 5 in thefollowing respects. More specifically, the apparatus shown in FIG. 6 hasa single additive auxiliary cup 14 including a load cell 12 in place ofthe additive auxiliary cups 14a to 14c, and a large charge storage cup 1is formed by a main charge storage cup 1a having a gate 8a and asubtractive auxiliary cup 1b having a gate 8b. The articles for largecharging are supplied to the main charge storage cup 1a and to thesubtractive auxiliary cup 1b separately. The articles fed into the maincharge storage cup 1a and the subtractive auxiliary cup 1b are weighedby load cells 7a and 7b. In FIG. 6, the same reference numbers designatethe same components as in FIG. 5.

The capacities of the additive auxiliary cup 14 and subtractiveauxiliary cup 1b are set to the range of +-a whose center is 6.4a inwhich the maximum dispersion ratio of the bulk densities of the articlesZ=-0.2, m=5 and s=2 are substituted for 2dV_(max) =2Zas^(m-1). Accordingto the present example, the capacity of the additive auxiliary cup 14and the capacity of the subtractive auxiliary cup 1b is 6.4a.

The functions of the additive auxiliary cup 14 and subtractive auxiliarycup 1b will be described below with reference to FIGS. 7 and 8. FIG. 7shows the case where the articles having the maximum bulk density of1+Z=1.2 are supplied into the additive storage cups 4a to 4d, and thearticles having the minimum bulk density of 1-Z=0.8 are supplied intothe additive storage cup 4e. FIG. 7 (a) shows the case where thearticles for additive charging are increased every minimum unit capacityby changing the combination of the additive storage cups. At A1, theadditive storage cups 4b to 4d are selected and the articles foradditive charging of (2+4+8)×1.2=16.8ad (a capacity ratio of 14) areprepared. For simplicity, ad is omitted in FIGS. 7 and 8. At A2, theadditive storage cup 4a having the minimum unit volume is added and thearticles for additive charging have a weight of 18.0ad (a capacity ratioof 15), which is the total weight of the articles within the additivestorage cups 4a to 4d. If the capacity ratio of the articles for theadditive charging storage cups are then increased to 16, only theadditive storage cup 4e is usually selected. Since articles having theminimum bulk density of 1-Z=0.8 are supplied into the additive storagecup 4e as described above, an additive weight of 12.8ad (16×0.8=12.8ad)is obtained at A3. Consequently, the weights of the articles foraddition are greatly decreased. According to the present example, thearticles within the additive auxiliary cup 14 are added, which providesa total additive weight of 19.2ad, (12.8+6.4=19.2ad), as shown by B1 ofFIG. 7(b). Thus, a gap (i.e., large step change) in the charging weightdifference of the articles for addition can be corrected.

FIG. 8 shows the case where the articles having the minimum bulk densityof 1-Z=0.8 are supplied into the additive storage cups 4a to 4d, and thearticles having the maximum bulk density of 1+Z =1.2 are supplied intothe additive storage cup 4e. FIG. 8(a) shows the case where the articlesfor addition are increased every minimum unit capacity by changing thecombination of the additive storage cups. At C1, the additive storagecups 4b to 4d are selected and the articles for addition of(2+4+8)×0.8=11.2ad (a capacity ratio of 14) are prepared. At C2, theadditive storage cup 4a having the minimum unit volume is added and thearticles for addition have a weight of 12.0ad (a capacity ratio of 15)which is the total weight of the articles within the additive storagecups 4a to 4d. Subsequently, if the capacity ratio of the articles forthe additive storage cups is increased to 16, only the additive storagecup 4e is usually selected. Since the articles having the maximum bulkdensity of 1+Z=1.2 are supplied into the additive storage cup 4e asdescribed above, 16×1.2=19.2ad is obtained at C3 so that the weights ofthe articles for addition are greatly increased. According to thepresent example, if the articles within the subtractive auxiliary cup 1bare not discharged, an additive weight of 12.8ad (19.2-6.4=12.8ad) isobtained at D1 shown in FIG. 8(b). Consequently, a gap (i.e., largechange) in the charging weight difference of the articles for additioncan be corrected.

While five additive storage cups having a capacity ratio of 1:2:4:8:16have been described in the above example, the present invention is notrestricted thereto but can be applied to an apparatus including aplurality of additive storage cups which have at least two differentcapacities. In addition, the number of the additive auxiliary cups canvary.

While the positive real numbers s and t are 2 in the above example, thepresent invention is not restricted thereto; other integers or decimalnumbers can be selected. Furthermore, the positive real numbers s and t,and b and a may be different from each other respectively. In this case,the difference in charging weight which is obtained by only the additivestorage cups is not the same as the difference in charging weight whichis obtained by adding the additive auxiliary cup.

In the quantitative charging apparatus according to the presentinvention, the large increase in the charging weight difference causedby changing the bulk densities of the articles supplied into theadditive storage cups is corrected by the additive auxiliary cup havingthe number and capacity corresponding to the gap. This allows the weightto be adjusted finer (more precisely) within a wide range even if thebulk densities of the articles in the storage cups vary.

According to the embodiment of the present invention in which thesubtractive auxiliary cup is provided, the articles within thesubtractive auxiliary cup are not discharged but held so that themaximum charging weight difference W_(max) can be decreased.Consequently, the weight delivered by the system is very accurate withina wide range.

While the invention has been described in detail, the foregoingdescription is in all aspects illustrative and not restrictive. It isunderstood that numerous other modifications and variations can bedevised without departing from the scope of the invention.

What is claimed is:
 1. A quantitative charging apparatus for deliveringquantities of articles with each quantity being of an acceptable weightrelative to a target weight W., said apparatus comprising:a large chargestorage cup provided with weighing means for storing articles having aweight which is smaller than and close to said target weight, aplurality of additive storage cups each provided with weighing means,said additive storage cups having at least two different capacities forstoring different predetermined volumes of articles for additivecharging with even-cupful so as to make up an underweight obtained bysubtracting the weight of articles within said large charge storage cupfrom said target weight, a control device for selecting a combination ofweights close to said underweight among the combinations of weights ofarticles in said additive storage cups, said combinations of weightschanging in stepwise manner according to predetermined charge weightdifferences based on the predetermined volumes of said additive storagecups, and one or more additive auxiliary cups, each provided withweighing means, for holding quantities of articles, said control devicebeing operable to use one or more of said additive auxiliary cups inselecting said combination close to said underweight if:(a) there is achange of predetermined magnitude in said predetermined charge weightdifferences due to a variation of bulk density of the articles in saidadditive storage cups; and (b) there is no acceptable combination ofweights based on the weights in said additive storage cups.
 2. Thequantitative charging apparatus of claim 1 wherein said additive storagecups include at least m additive storage cups having the followingcapacity:a, as¹, as², . . . , as^(k-1), . . . , as^(m-1) a: the capacityof the additive storage cup as a reference s: a positive real number 0<k(integer)<=m, m<=the number of said additive storage cups.
 3. Thequantitative charging apparatus of claim 2 wherein said additiveauxiliary cup is a single cup, and said additive auxiliary cup and asubtractive auxiliary cup have capacities which can store the articleshaving a weight of (2ZdV_(max) -ad) to (2ZdV_(max) +ad) when the maximumvolume of said additive storage cups is V_(max), the maximum dispersionratio of the bulk densities of the articles within said additive storagecups is Z, and the reference value of the bulk density of the articlesis d.
 4. The quantitative charging apparatus of claim 2 wherein saidadditive auxiliary cups include at least p additive auxiliary cupshaving the following capacity:b, bt¹, bt², . . . , bt^(k-1), . . . ,bt^(p-1) b: the capacity of the additive auxiliary cup as a reference t:a positive real number < k (integer)<=p.
 5. The quantitative chargingapparatus of claim 4 wherein said positive real numbers t and s areequal to each other.
 6. The quantitative charging apparatus of claim 5wherein said positive real numbers t and s are
 2. 7. The quantitativecharging apparatus of claim 6 wherein when the maximum dispersion ratioof the bulk densities of the articles within said additive storage cupsis Z, the maximum volume of said m additive storage cups is V_(max), andthe total capacity of said p additive auxiliary cups is A, the number pof said additive auxiliary cups is an integer which satisfies thefollowing equation: ##EQU6##
 8. The quantitative charging apparatus ofclaim 2 wherein said additive auxiliary cups include at least p additiveauxiliary cups having the following capacity: b, bt¹, bt², . . . ,bt^(k-1), . . . , bt^(p-1) b: the capacity of the additive auxiliary cupas a reference t: a positive real number 0<k (integer)<=p.
 9. Thequantitative charging apparatus of claim 8 wherein said positive realnumbers t and s are equal to each other.
 10. The quantitative chargingapparatus of claim 9 wherein said positive real numbers t and s are 2.11. The quantitative charging apparatus of claim 10 wherein when themaximum dispersion ratio of the bulk densities of the articles withinsaid additive storage cups is Z, the maximum volume of said m additivestorage cups is V_(max), and the total capacity of said p additiveauxiliary cups is A, the number p of said additive auxiliary cups is aninteger which satisfies the following equation: ##EQU7##
 12. Thequantitative charging apparatus of claim 1 wherein said control deviceis operable to select one or more of said additive auxiliary storagecups only when said change in said predetermined charge weightdifferences exceeds a predetermined amount.